I want to mention this one simple because of the way it starts out so well, with some terrific location filming and special effects; and ends up so poorly in a studio full of cardboard props and Sinclair ZX quality “special” effects.
Much of the story takes place in a nuclear power station (actually filmed in a real power station, and it shows). Sarah Jane is possessed, an over-used and irritating device with other characters, but Lis Sladen carries it off rather well (in pink dungarees). In fact her performance here is excellent, far more relaxed than earlier serials (think Felicity Kendall as Barbara Good). The titular hand, when it becomes animated, is seriously scary. The nuclear power station scenes are remnicent of The China Syndrome, and although it doesn’t compare that favourably (unsurprisingly) I was quite impressed to discover it actually pre-dates it by 3 years.
Lennie Mayne’s direction, especially in episode one, is first class. Judith Paris is a wonderful alien, but the serial’s decline (in plot and production values) towards the end is exemplified by her regeneration into the dull, shouty Stephen Thorne. A pity when it started out so well. But that’s why it’s only remembered as The One Where Sarah Jane Leaves.